SECT. 2] LARGE-SCALE INTERACTIONS 



Table XV 



()ceaii Surface Stress Determinations from Weather Ship C Wind Data 



52° 45'N, 35° 30'W 



February 26-March 19, 1960 



p = 1.27 X 10-3 g cm-3 



189 



Method 



Surface stress 



Direction, 

 ° from N 



Magnitude, 

 dyne/cm2 



I. Direct summation 



Solid curve, Fig. 6 

 Dashed curve, Fig. 6 



II. Wind rose 



Scripps Pacific 

 Scripps Atlantic 

 Mod. Scripps Atlantic 



(cj) solid curve. Fig. 6) 

 Winds from crew's log 



(in Beaufort, vising Scripps Pacific) 



TO = pCDUa^ Mean wind speed for period 

 TO = pODUa^ Resultant wind for period 



Resultant wind for period: 015°, 7.8 m/sec 

 Average wind speed for period: 11.3 m/sec 

 Directional wind steadiness for period: 69% 



004 

 006 



007 

 Oil 

 004 



350 



015 



3.3 

 3.65 



3.7 

 3.4 

 3.0 



3.0 



3.65 

 1.3 



meaningful surface stresses from ordinary merchant ship reports. The stress 

 computed from the resultant wind is more than a factor of two down, as 

 expected with the smaller wind steadiness. 



Comparison with the climatic mean stress for the period exemplifies the time 

 variations in stress which may be expected in high latitudes. Unfortunately, 

 the Scripps monthly maps showed no data for the location of Weather Ship C, 

 but the appropriate wind roses are shown in Figs. 44d and e. The Scripps method 

 gives a mean stress for February of 1.85 dynes/cm^ at 235° and for March, 

 1.81 dynes/cm^ at 238°. The three weeks studied thus showed stronger and more 

 northerly wind stresses than the climatic average. That the period was ex- 

 tremely stormy was attested to by the battered condition of the ship and 

 reports of its crew upon return to port. Although the stress magnitude in the 

 period selected is only twice as large as the climatic average, the directions 

 depart by more than 120° and the vector difference exceeds the size of either 

 stress. This is in complete contrast to the tropical situation and of considerable 

 consequence to oceanography. A very good estimate of the representativeness 

 of climatic stress distributions and the meteorological dynamics of their 



